1. Field of the Invention
The present invention relates to an electrophoretic particle, a display device including the particle, and a method thereof. More particularly, the present invention relates to an electrophoretic particle having a structure that increases a response speed and efficiently prevents agglomerating with other particles, a display device using the particle, and a method thereof.
2. Description of the Related Art
One type of display employs capsules that store charged solid particles and a solution in which the solid particles are dispersed. The solid particles disposed between two electrodes forming an electric field are moved by the electric field formed by the two electrodes, and thus they are referred to as electrophoretic type particles. Such a display, hereinafter referred to as a “first type of display”, is suggested by E-INK Corp.
Another type of display employs a structure in which the solid particles are dispersed in unit cells defined by ribs disposed between two substrates. Since air exists in the unit cells, the solid particles are dispersed in air. The solid particles in the unit cells are not charged in a normal status. When an electric field is generated in response to voltages applied between electrodes formed on both substrates, surface charges are generated on the surfaces of the solid particles that exist in the electric field area. Such a display, hereinafter referred to as a “second type of display”, is suggested by Bridge Stone Corp.
The first and second types of displays are reflective displays. According to the first type of display, the response speed is about 30 to 200 ms, which is slow, and the moving speed of the solid particles becomes slower when an operating temperature is lowered because of the flow resistance of the liquid when the solid particles move in the liquid and a viscosity of the liquid that increases when the temperature decreases.
On the other hand, in the second type of display, since the solid particles move in air, the response speed is faster than in the first type of display, that is, 0.2 ms or faster. However, since there are not many charges on the surfaces of the solid particles that are dispersed in air, a high voltage of about 70V is required to move the solid particles. In particular, since the positive solid particles and the negative solid particles in air are mixed in each of the unit cells, the positive solid particles and the negative solid particles can stick to each other. Sticking occurs more in the second type of display than in the first type of display because an air shock-absorbing function for preventing sticking between the solid particles of opposite polarities is weaker than that of liquid.